Chris Weidman, Ronda Rousey are big favorites for UFC bouts Saturday

Chris Weidman celebrates with the U.S. flag draped over his shoulders after defeating Anderson Silva by technical knockout to retain his middleweight title at UFC 168 in Las Vegas.

Chris Weidman celebrates with the U.S. flag draped over his shoulders after defeating Anderson Silva by technical knockout to retain his middleweight title at UFC 168 in Las Vegas. (David Becker / Associated Press)

Chris Weidman says his UFC opponent, Lyoto Machida, is a more well-rounded fighter than Anderson Silva

Chris Weidman and Ronda Rousey are a combined 20-0 in mixed martial arts fights. Each owns an Ultimate Fighting Championship belt they will defend Saturday night in Las Vegas.

Middleweight champion Weidman (11-0), who'll be challenged by former UFC light-heavyweight belt-holder Lyoto Machida at Mandalay Bay, has never been taken down and is coming off two consecutive victories over the man long considered the organization's best fighter, Anderson Silva.

Rousey (9-0) has ended eight of her fights in the first round and won eight by armbar submission. Her next opponent is second-ranked Alexis Davis, who's lost five MMA fights.

The names of the opponents are necessary to sell tickets and pay-per-view orders, but Weidman's and Rousey's unnamed foes of overconfidence and complacency are also adversaries for the dominating champions.

"There's always things you can get better at, things I need to work on, and things I worry about," said Weidman, who had to delay the Machida fight from late May because he required surgery on both knees for meniscus tears. "I'm not complacent. I always believe I can be beaten at any point just like anyone else."

Rousey similarly is fueled by an inner drive that stems from her belief she's vulnerable to squandering the commercial success that has landed her three film roles in the past year.

"I never feel overly confident," Rousey said. "That's why I work so much harder than all these girls. I always think of that worse-case scenario. To fail now would be like tripping at the finish line. It's just something I can't allow to happen.

"There's never been any more on the line than there is in this fight against Alexis."

While no one with the exception of February technical knockout victim Sara McMann has been able to avoid Rousey's famed armbar, the Venice fighter says she's concerned by Davis' striking and grappling skills.

Meanwhile, Weidman said he respects Machida's karate and wrestling, and his ability to fight "slippery." The Brazilian-born Machida often plots on his feet, seeking a path to victory with minimal exchanges — even if the boring style routinely elicits a chorus of boos.

"He's OK with winning decisions, he's OK with winning close decisions … I have to be aware of that," Weidman said. "I don't feel good letting a fight get to the judges. Every time I've had a good training camp, I've finished my guy, and I plan on doing that."

Weidman is more aggressive, boasting 68% takedown success, seven submissions and three consecutive knockouts. Silva lost the recent meeting by breaking his leg while checking a Weidman kick.

Weidman said another victory is essential to boost his own brand. He ranks near the top with light-heavyweight champion Jon Jones and featherweight champion Jose Aldo in most UFC pound-for-pound rankings.

"I actually think Lyoto is a more well-rounded fighter than Anderson," Weidman said. "I go out there with the wrong focus, and I'm losing. I'm not taking this fight lightly at all.

"I'll use my wrestling, my ground game, pressure and cardio. Anything I can do to break him … I want to dominate this division. I want to be known as one of the greatest ever."

Rousey, meanwhile, said this training camp was her most focused and seamless after finishing filming for the "Entourage" movie.

"I'm expecting her [Davis] to go short elbows whenever I try to clench," Rousey said, "and for her to expect my same posture as McMann, to try some left head kicks to keep me away. I'm preparing for all the scenarios. Nothing ever distracts me from training."

Rousey said she lets UFC President Dana White deal with talks with better-known possible foes Cris "Cyborg" Justino and Gina Carano, and insists the UFC has some serious challengers to her dominance.

"Just because the girls aren't that well known doesn't mean they're not accomplished athletes," Rousey said. "Alexis Davis doesn't have a public Instagram account. That doesn't mean she's not a great fighter."